This project involves the use of X-ray photoelectron Spectroscopy (XPS) to probe the electronic structure of porphyrins and heme proteins. It also involves the use of XPS as an analytical tool in the study of porphyrin compounds bound upon surfaces, principally prepared oxide surfaces (glass and alumina). The current emphasis in the area of electronic structure are in the acquisition of core binding energy data from porphyrins in the vapor phase in order to obtain better resolution and to observe the C 1s features free of contamination. A secondary emphasis is in a calculational effort designed to integrate data on the valence-electron structure of porphyrins, such as the excited valence states reached on core ionization and the distribution of metal D orbital derived levels observed in valence region spectroscopy, into the theoretical ideas on porphyrins. The analytical application of XPS has electronic structure as an eventual goal. It is now, however, restricted primarily to definition of surface species. We have prepared glass surfaces (and to a lesser extent, alumina surfaces) covered with groupings of the type (triple bond Si-(CH2)3R with R equals NH2, -N imidazole N, -SH, SNa plus, -SCH3, -N(double bond) CS2 NA plus, using standard techniques. We have then attempted to study the reactions of these groupings with porphyrins, heretofore primarily Fe(II) and Fe(III) porphyrins. The eventual object of these studies is the production of models of biological heme compounds for the study of their electronic structures.